I am stuck on trying to find out which to buy. I recently lost a 17' rev A powerbook in a home robbery. It basically was my life since I am a Ph.D. student writing my dissertation. Thank god for back-ups. It has been very traumatic but now with the option of buying a replacement computer (insurance please come through!) I am stuck between considering buying another 17' powerbook or the 20' iMac. I really like the large workspace and the ability to have at least two full windows open is a godsend and a necessity. My questions are: 1. Will I see a noticeable difference in performance between a 17"pb and a 20" imac? (I don't own a desktop and doing some video, dvd burning, etc. was sometimes pretty labor intensive for the 17", I also came close to filling my hd in the last year) 2. Provided I needed to actually move, which frequently happens, is the iMac 20" somewhat portable? Could I fit it in a case and bring it carry-on for an airline. I am currently working abroad and can't see one so I don't know the actual dimensions once you remove the stand. I'd really like to make the purchase and hopefully have it awaiting my return at the end of the month. 3. Let's say I buy the 20" to use for now with the thought that I will eventually by a new powerbook g5. What is the normal timeline on these things in years? Advice. Advice. Please.